1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * Copyright (c) 2008 Intel Corporation |
4 | * Author: Matthew Wilcox <willy@linux.intel.com> |
5 | * |
6 | * Please see kernel/locking/semaphore.c for documentation of these functions |
7 | */ |
8 | #ifndef __LINUX_SEMAPHORE_H |
9 | #define __LINUX_SEMAPHORE_H |
10 | |
11 | #include <linux/list.h> |
12 | #include <linux/spinlock.h> |
13 | |
14 | /* Please don't access any members of this structure directly */ |
15 | struct semaphore { |
16 | raw_spinlock_t lock; |
17 | unsigned int count; |
18 | struct list_head wait_list; |
19 | }; |
20 | |
21 | #define __SEMAPHORE_INITIALIZER(name, n) \ |
22 | { \ |
23 | .lock = __RAW_SPIN_LOCK_UNLOCKED((name).lock), \ |
24 | .count = n, \ |
25 | .wait_list = LIST_HEAD_INIT((name).wait_list), \ |
26 | } |
27 | |
28 | /* |
29 | * Unlike mutexes, binary semaphores do not have an owner, so up() can |
30 | * be called in a different thread from the one which called down(). |
31 | * It is also safe to call down_trylock() and up() from interrupt |
32 | * context. |
33 | */ |
34 | #define DEFINE_SEMAPHORE(_name, _n) \ |
35 | struct semaphore _name = __SEMAPHORE_INITIALIZER(_name, _n) |
36 | |
37 | static inline void sema_init(struct semaphore *sem, int val) |
38 | { |
39 | static struct lock_class_key __key; |
40 | *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); |
41 | lockdep_init_map(lock: &sem->lock.dep_map, name: "semaphore->lock" , key: &__key, subclass: 0); |
42 | } |
43 | |
44 | extern void down(struct semaphore *sem); |
45 | extern int __must_check down_interruptible(struct semaphore *sem); |
46 | extern int __must_check down_killable(struct semaphore *sem); |
47 | extern int __must_check down_trylock(struct semaphore *sem); |
48 | extern int __must_check down_timeout(struct semaphore *sem, long jiffies); |
49 | extern void up(struct semaphore *sem); |
50 | |
51 | #endif /* __LINUX_SEMAPHORE_H */ |
52 | |